Though it has sometimes been shown that events encoded in a certain state of affect or mood are more retrievable In a similar state than in a dissimilar one, neither the circumstances under which mood dependent memory occurs, nor the mechanisms that enable Its emergence, are as yet well understood. The purpose of the present project is to clarify these circumstances and mechanisms. To this end, the proposed research focuses on five factors that appear to play pivotal roles in the manifestation of mood dependent memory. These factors are (a) the degree and durability of mood modification (for instance, does the transition from, say, a pleasant mood at encoding to an unpleasant mood at retrieval impair memory more than does a shift from a pleasant to a neutral affect?), (b) the nature of the encoding task (are events generated through internal mental processes such as reasoning, imagination, or thought more apt to be forgotten following a shift in mood state than are events that emanate mainly from external sources?), (c) the nature of the retrieval task (is it possible to demonstrate mood dependence using implicit rather than explicit measures of memory?), (d) one-dimensional versus two-dimensional alterations in affect (does a shift along both the pleasure/displeasure and arousal/sleepiness dimensions of mood produce a more pronounced memory deficit than does a shift along the pleasure dimension alone?), and (e) the duration of the retention interval (do mood dependent effects in memory become stronger--not weaker--as the span separating encoding and retrieval becomes longer?). By exploring these five factors in a rigorous and programmatic fashion, the proposed research should resolve much of the controversy that now surrounds mood dependent memory, and provide fresh insights into the phenomenon's cognitive and affective foundations.